Alvin Chang wrote:
On 05/01/07, Aleksandar Milivojevic <alex@xxxxxx> wrote:
I've used it, and it works correctly (and it is available in CentOS
4.4). It shrinks file system as it should. The only things Paul should
be careful is to first shrink file system, than logical volume and to
correctly calculate file system size and by how many extents he can
shrink logical volume. If he shrinks logical volume too much, he might
end up loosing data. Running fsck in non-destructive mode (fsck -N)
and/or attempting to mount file system read-only after he shrinks
logical volume might be a good idea to test all is OK.
A little technique you can use is:
1. shrink the file system to the size slightly less than what you
really want
2. reduce LV to the size that is what you really want
3. expand the file system to the size of the LV (usually the resize
program can be told to expand the file system to maximum available
space automatically on the LV.)
That sounds like a pretty healthy tip!
Keep in mind that with a large LV, the slowest part of this process is
often the fsck -f step.
The resize2fs command is not nearly as slow as the fsck -f. But on a
large LV, you prolly want to show the progress bar during the resize, so
do a resize2fs -p, because I know I get nervous when I don't see output
from a long running command.
On production systems, I've learned to have enough space to have one
empty LV that can hold any of the other LVs so you can cleverly remount
a copy of the LV you want to either fsck or recreate. I don't want to
have a 2-hour reboot after 200 days uptime just to have my filesystem
force a fsck -f on you when you very like least want it. Recreating a LV
is a clever way to get around doing regular fscking, unless you tune
your filesystem check way out to 3 years and 999 reboots or whatnot.
Jed
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